A Novel In Vitro Pathological Model for Studying Neural Invasion in Non-Melanoma Skin Cancer.

Neural Invasion (NI) is a key pathological feature of cancer in the colonization of distant tissues, and its underlying biological mechanisms are still scarcely known. The complex interactions between nerve and tumor cells, along with the stroma, make it difficult to reproduce this pathology in effective study models, which in turn has limited the understanding of NI pathogenesis. In this study, we have designed a three-dimensional model of NI squamous cell carcinoma combining human epidermoid carcinoma cells (hECCs) with a complete peripheral nerve segment encapsulated in a fibrine-agarose hydrogel. We recreated two vital processes of NI: a pre-invasive NI model in which hECCs were seeded on the top of the nerve-enriched stroma, and an invasive NI model in which cancer cells were immersed with the nerve in the hydrogel. Histological, histochemical and immunohistochemical analyses were performed to validate the model. Results showed that the integration of fibrin-agarose advanced hydrogel with a complete nerve structure and hECCs successfully generated an environment in which tumor cells and nerve components coexisted. Moreover, this model correctly preserved components of the neural extracellular matrix as well as allowing the proliferation and migration of cells embedded in hydrogel. All these results suggest the suitability of the model for the study of the mechanisms underlaying NI.

Expression of Basement Membrane Molecules by Wharton Jelly Stem Cells (WJSC) in Full-Term Human Umbilical Cords, Cell Cultures and Microtissues.

Wharton's jelly stem cells (WJSC) from the human umbilical cord (UC) are one of the most promising mesenchymal stem cells (MSC) in tissue engineering (TE) and advanced therapies. The cell niche is a key element for both, MSC and fully differentiated tissues, to preserve their unique features. The basement membrane (BM) is an essential structure during embryonic development and in adult tissues. Epithelial BMs are well-known, but similar structures are present in other histological structures, such as in peripheral nerve fibers, myocytes or chondrocytes. Previous studies suggest the expression of some BM molecules within the Wharton's Jelly (WJ) of UC, but the distribution pattern and full expression profile of these molecules have not been yet elucidated. In this sense, the aim of this histological study was to evaluate the expression of main BM molecules within the WJ, cultured WJSC and during WJSC microtissue (WJSC-MT) formation process. Results confirmed the presence of a pericellular matrix composed by the main BM molecules-collagens (IV, VII), HSPG2, agrin, laminin and nidogen-around the WJSC within UC. Additionally, ex vivo studies demonstrated the synthesis of these BM molecules, except agrin, especially during WJSC-MT formation process. The WJSC capability to synthesize main BM molecules could offer new alternatives for the generation of biomimetic-engineered substitutes where these molecules are particularly needed.

Injectable Magnetic-Responsive Short-Peptide Supramolecular Hydrogels: Ex Vivo and In Vivo Evaluation.

The inclusion of magnetic nanoparticles (MNP) in a hydrogel matrix to produce magnetic hydrogels has broadened the scope of these materials in biomedical research. Embedded MNP offer the possibility to modulate the physical properties of the hydrogel remotely and on demand by applying an external magnetic field. Moreover, they enable permanent changes in the mechanical properties of the hydrogel, as well as alterations in the micro- and macroporosity of its three-dimensional (3D) structure, with the associated potential to induce anisotropy. In this work, the behavior of biocompatible and biodegradable hydrogels made with Fmoc-diphenylalanine (Fmoc-FF) (Fmoc = fluorenylmethoxycarbonyl) and Fmoc-arginine-glycine-aspartic acid (Fmoc-RGD) short peptides to which MNP were incorporated was studied in detail with physicochemical, mechanical, and biological methods. The resulting hybrid hydrogels showed enhance mechanical properties and withstood injection without phase disruption. In mice, the hydrogels showed faster and improved self-healing properties compared to their nonmagnetic counterparts. Thanks to these superior physical properties and stability during culture, they can be used as 3D scaffolds for cell growth. Additionally, magnetic short-peptide hydrogels showed good biocompatibility and the absence of toxicity, which together with their enhanced mechanical stability and excellent injectability make them ideal biomaterials for in vivo biomedical applications with minimally invasive surgery. This study presents a new approach to improving the physical and mechanical properties of supramolecular hydrogels by incorporating MNP, which confer structural reinforcement and stability, remote actuation by magnetic fields, and better injectability. Our approach is a potential catalyst for expanding the biomedical applications of supramolecular short-peptide hydrogels.

Generation of a novel model of bioengineered human oral mucosa with increased vascularization potential.

OBJECTIVE: The aim of this study was to generate novel models of bioartificial human oral mucosa with increased vascularization potential for future use as an advanced therapies medicinal product, by using different vascular and mesenchymal stem cell sources. BACKGROUND: Oral mucosa substitutes could contribute to the clinical treatment of complex diseases affecting the oral cavity. Although several models of artificial oral mucosa have been described, biointegration is a major issue that could be favored by the generation of novel substitutes with increased vascularization potential once grafted in vivo. METHODS: Three types of mesenchymal stem cells (MSCs) were obtained from adipose tissue, bone marrow, and dental pulp, and their in vitro potential was evaluated by inducing differentiation to the endothelial lineage using conditioning media. Then, 3D models of human artificial oral mucosa were generated using biocompatible fibrin-agarose biomaterials combined with human oral mucosa fibroblasts and each type of MSC before and after induction to the endothelial lineage, using human umbilical vein endothelial cells (HUVEC) as controls. The vascularization potential of each oral mucosa substitute was assessed in vitro and in vivo in nude mice. RESULTS: In vitro induction of MSCs kept in culture was able to increase the expression of VEGF, CD31, and vWF endothelial markers, especially in bone marrow and dental pulp-MSCs, and numerous proteins with a role in vasculogenesis become overexpressed. Then, in vivo grafting resulted in a significant increase in blood vessels formation at the interface area between the graft and the host tissues, with significantly positive expression of VEGF, CD31, vWF, and CD34 as compared to negative controls, especially when pre-differentiated MSCs derived from bone marrow and dental pulp were used. In addition, a significantly higher number of cells committed to the endothelial lineage expressing the same endothelial markers were found within the bioartificial tissue. CONCLUSION: Our results suggest that the use of pre-differentiated MSCs could contribute to a rapid generation of a vascular network that may favor in vivo biointegration of bioengineered human oral mucosa substitutes.